:root{--bg:#f8f9f6;--paper:#fff;--ink:#25332d;--muted:#7c857f;--line:#e6eae3;--green:#387258;--pale:#eaf1e8;--reading-size:17px;font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Helvetica Neue",sans-serif;color:var(--ink);background:var(--bg);font-synthesis:none}*{box-sizing:border-box}body{margin:0}button,input,select,textarea{font:inherit}button,a,input,select,textarea{-webkit-tap-highlight-color:transparent}button{cursor:pointer;color:inherit}button{background:none;border:0}button:disabled{opacity:.42;cursor:default}button:focus-visible,a:focus-visible,summary:focus-visible{outline:2px solid var(--green);outline-offset:3px}input:focus,textarea:focus,select:focus{outline:2px solid 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p{font-size:12px;color:var(--muted);margin-top:8px}.primary,.secondary{display:inline-flex;align-items:center;justify-content:center;gap:10px;min-height:40px;border-radius:7px;padding:11px 20px;font-size:12px;white-space:nowrap}.primary{background:var(--green);color:#fff}.primary:hover:not(:disabled){background:#2b6048}.primary .icon{width:16px;height:16px}.secondary{border:1px solid #d9e0d6;background:#fff}.secondary:hover{background:var(--pale)}.text-button{display:inline-flex;align-items:center;justify-content:center;gap:7px;font-size:12px;color:var(--green);padding:10px 0;min-height:36px}.text-button:hover{text-decoration:underline;text-underline-offset:4px}.text-button 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summary::-webkit-details-marker{display:none}.compact-note summary .icon{width:14px;height:14px}.compact-note summary span{color:#b0b6aa;font-size:10px;margin-left:5px}.compact-note textarea{width:100%;resize:vertical;min-height:62px;margin-top:11px;border:0;border-bottom:1px solid #dce3d7;background:#fafbf8;font-size:12px;line-height:1.8;color:var(--ink);padding:8px 10px;display:block;border-radius:4px}.mastery-label{display:flex;flex-direction:column;font-size:9px;color:#adb4a5;gap:5px;flex-shrink:0;max-width:93px}.mastery-label select{border:0;font-size:10px;color:#76836e;background:transparent;padding:5px 0;max-width:90px}.question-footer{font-size:9px;color:#b6bdb0;display:flex;gap:12px;justify-content:space-between;line-height:1.9;margin-top:35px}.content-notice{font-size:11px;color:#a27853;background:#fcf8ed;padding:12px 15px;margin-bottom:20px;line-height:1.9}.blank{padding:55px 25px;color:var(--muted);text-align:center}.blank h2{font-size:16px}.blank p{font-size:12px;margin-top:15px}.question-body img,.solution img{max-width:100%;height:auto;display:block;margin:7px 0;cursor:zoom-in}.prerequisite{font-size:12px;padding:15px 0}.prerequisite summary{cursor:pointer;color:var(--green)}.diagram-dialog{max-width:96vw;width:1100px;max-height:94dvh;border:0;border-radius:8px;padding:15px;background:#fff}.diagram-dialog::backdrop{background:#15251bb3}.diagram-dialog>button{display:block;margin-left:auto;margin-bottom:12px}.diagram-scroll{overflow:auto;max-height:calc(90dvh - 80px)}.diagram-scroll img{max-width:none;min-width:100%;display:block}.stats-layout{display:grid;grid-template-columns:1.35fr 1fr;gap:45px;padding:38px 0 45px}.calendar-section{min-width:0}.calendar-section .section-heading{margin-bottom:22px}.month-control{display:flex;align-items:center;gap:9px}.month-control strong{font-size:11px;font-weight:500;white-space:nowrap}.month-control .icon-button{min-width:25px}.calendar-grid{display:grid;grid-template-columns:repeat(7,minmax(0,1fr));gap:5px}.week-label{text-align:center;color:#969f90;font-size:10px;margin-bottom:10px}.calendar-day{aspect-ratio:1;min-height:42px;border-radius:5px;padding:8px 0;display:flex;flex-direction:column;gap:6px;align-items:center;justify-content:center;border:1px solid transparent;position:relative}.calendar-day>span{font-size:12px;font-variant-numeric:tabular-nums}.calendar-day>small{font-size:8px;height:10px}.calendar-day.today>span{font-weight:750;text-decoration:underline;text-underline-offset:3px}.calendar-day.selected{border-color:var(--green);box-shadow:inset 0 0 0 1px var(--green)}.calendar-legend{display:flex;align-items:center;gap:5px;margin-top:15px;font-size:9px;color:var(--muted)}.calendar-legend i{height:10px;width:10px;border-radius:2px}.calendar-legend .text-button{margin-left:auto;font-size:10px;min-height:25px}.daily-section{min-width:0;border-left:1px solid var(--line);padding-left:28px}.daily-rate{padding:18px 0 22px;border-bottom:1px solid var(--line);display:flex;flex-direction:column;gap:8px}.daily-rate strong{font-size:34px;font-weight:450;letter-spacing:-1px}.daily-rate span{font-size:10px;color:var(--muted)}.daily-attempts{max-height:355px;overflow:auto}.daily-attempt{display:flex;align-items:center;gap:10px;text-align:left;width:100%;padding:14px 0;border-bottom:1px solid var(--line)}.daily-attempt>span{font-size:11px}.daily-attempt small{display:block;font-size:9px;color:var(--muted);margin-top:6px}.daily-attempt time{margin-left:auto;font-size:9px;color:#a0a89a;white-space:nowrap}.subject-stat{display:flex;align-items:center;gap:20px;min-height:64px;border-bottom:1px solid var(--line)}.subject-stat strong{font-size:12px;font-weight:500;width:135px}.subject-stat-progress{flex:1;max-width:180px;height:3px;background:#e9ede3}.subject-stat-progress i{display:block;height:3px;min-width:0;max-width:100%}.subject-stat>span:not(.subject-dot):not(.subject-stat-progress){font-size:10px;color:var(--muted);margin-left:auto}.subject-stat b{font-size:14px;font-weight:500;min-width:40px;text-align:right}.stats-footnote{margin-top:25px;max-width:730px}.settings-page{max-width:900px}.settings-page>h1{margin-top:12px;margin-bottom:15px}.settings-section{padding:30px 0;border-bottom:1px solid var(--line)}.settings-section h2{font-size:16px;margin-bottom:14px}.settings-section p{font-size:12px;color:var(--muted);margin-bottom:13px;max-width:700px}.settings-actions{display:flex;flex-wrap:wrap;gap:15px;margin-top:24px}.font-setting{display:flex;align-items:center;gap:20px;font-size:12px;color:var(--muted)}input[type=range]{accent-color:var(--green)}.settings-section table{width:100%;border-collapse:collapse;font-size:12px;margin-top:20px;text-align:left}.settings-section td,.settings-section th{padding:14px 0;border-bottom:1px solid var(--line);font-weight:400}.settings-section th{color:var(--muted);font-size:10px}.lesson{height:100%;display:flex;flex-direction:column}.lesson-toolbar{padding:22px 35px;display:flex;justify-content:space-between;align-items:center;gap:20px;border-bottom:1px solid var(--line)}.lesson-toolbar h1{font-size:21px}.lesson-toolbar span{font-size:10px;color:var(--muted);display:block;margin-top:9px}.lesson-toolbar>div:last-child{display:flex;gap:25px}.lesson-layout{display:flex;flex:1;min-height:0}.lesson-toc{width:240px;overflow:auto;flex-shrink:0;padding:20px 13px;border-right:1px solid var(--line)}.lesson-toc button{display:block;text-align:left;width:100%;font-size:11px;line-height:1.7;padding:8px 13px;color:var(--muted)}.lesson-toc button:hover{color:var(--green);background:var(--pale)}.lesson-toc .level-2{font-weight:600;margin-top:10px}.lesson-toc .level-3{padding-left:23px;font-size:10px}#lesson-frame{flex:1;border:0;width:100%;min-width:0;background:#fcfbf8}#toc-toggle{display:none}#toast{position:fixed;bottom:28px;left:50%;transform:translate(-50%,8px);opacity:0;pointer-events:none;max-width:calc(100vw - 30px);padding:12px 20px;background:#2e4436;color:#fff;box-shadow:0 4px 25px #25332d1a;font-size:12px;border-radius:8px;line-height:1.7;z-index:80;transition:opacity .15s,transform .15s}#toast.visible{opacity:1;transform:translate(-50%,0)}.loading{padding:80px 30px;text-align:center;font-size:13px;color:var(--muted)}
@media(min-width:1600px){.detail-content{padding-top:42px}.question-list{width:320px}.topbar{padding-right:60px}.library-heading{padding-right:60px}}
@media(max-width:1200px){.sidebar{width:190px;padding-left:12px;padding-right:12px}.page{padding:40px 35px 65px}.topbar{padding:0 30px;gap:18px}.question-list{width:240px}.detail-content{padding:27px}.detail-toolbar{padding:11px 22px}.shelf-actions{gap:17px}.home-bottom{gap:35px}.library-heading{padding:24px 28px 20px}.filters{padding-left:28px;padding-right:28px}.stats-layout{gap:28px}.daily-section{padding-left:20px}.calendar-day{min-height:35px}.subject-stat{gap:13px}.subject-stat-progress{max-width:120px}}
@media(max-width:1000px){.sidebar{width:174px;padding-left:8px;padding-right:8px}.brand{gap:8px;margin-left:9px;margin-right:0}.brand strong{font-size:13px}.brandmark{width:30px;height:33px}.brand small{font-size:8px}.nav-item{font-size:11px;gap:9px;padding-left:12px;padding-right:9px}.nav-item .icon{width:16px;height:16px}.page{padding:34px 30px 60px}.topbar{height:67px;padding:0 27px}.searchbox{width:225px}.searchbox input{font-size:11px}.topbar kbd{display:none}.page-heading>.today{display:none}.page-heading h1{font-size:28px}.metrics{padding-top:28px}.metrics strong{font-size:29px}.metrics strong small{display:block;margin:5px 0 0;font-size:9px}.resume h2{font-size:18px}.resume .primary{padding:10px 15px}.subject-line{gap:15px}.subject-name h3{font-size:14px}.subject-name p{font-size:9px}.shelf-actions .course-link{display:none}.shelf-actions .text-button{font-size:11px}.subject-number{font-size:25px;min-width:32px}.home-bottom{grid-template-columns:1fr;gap:28px}.heatmap{grid-template-columns:repeat(28,1fr);margin-top:20px}.question-list{width:210px}.question-row{padding:13px 18px}.group-title{padding-left:18px}.detail-content{padding:23px}.question-heading{align-items:flex-start;flex-direction:column;gap:10px}.question-heading h2{font-size:18px}.source-line{margin-top:10px}.detail-toolbar{padding-left:22px;padding-right:18px}.library-actions{gap:15px}.stats-layout{grid-template-columns:1fr;gap:35px}.daily-section{border-left:0;padding-left:0;border-top:1px solid var(--line);padding-top:26px}.daily-attempts{max-height:260px}.daily-rate{padding:3px 0 15px}.calendar-day{aspect-ratio:1.15}.subject-stat-progress{display:none}.subject-stat strong{width:auto}.subject-stat{gap:11px}.lesson-toc{width:190px}.lesson-toc button{font-size:10px}.lesson-toolbar{padding:20px 25px}}
@media(max-width:760px){.sidebar{position:fixed;top:0;bottom:0;left:0;width:235px;z-index:60;padding:27px 18px;background:var(--bg);transform:translateX(-100%);transition:transform .18s}.nav-open .sidebar{transform:translateX(0)}.sidebar .brand{margin-bottom:35px}.sidebar .brandmark{width:35px;height:35px}.sidebar .brand strong{font-size:15px}.sidebar .brand small{font-size:10px}.sidebar .nav-item{font-size:13px;padding:12px}.sidebar .nav-item .icon{width:18px;height:18px}.nav-open #nav-backdrop{display:block;position:fixed;inset:0;background:#1e342945;z-index:50;width:100%;height:100%;backdrop-filter:blur(2px)}.topbar{height:62px;gap:12px;padding:0 19px}#menu-toggle{display:inline-flex;min-width:26px;min-height:34px;font-size:19px;margin-left:-6px}#breadcrumbs{display:none}.searchbox{width:auto;flex:1;margin:0 8px 0 0}.searchbox input{font-size:12px}.sync-state{font-size:9px}#mobile-nav{display:grid;grid-template-columns:repeat(4,1fr);height:calc(56px + env(safe-area-inset-bottom));padding-bottom:env(safe-area-inset-bottom);position:fixed;bottom:0;left:0;right:0;background:#f8f9f6f7;border-top:1px solid var(--line);backdrop-filter:blur(15px);z-index:30}#mobile-nav button{display:flex;flex-direction:column;align-items:center;justify-content:center;gap:4px;font-size:9px;color:#99a191}#mobile-nav .icon{width:19px;height:19px}#mobile-nav button.active{color:var(--green)}.workspace{padding-bottom:calc(56px + env(safe-area-inset-bottom))}.page{padding:29px 24px 45px}.eyebrow{font-size:8px;letter-spacing:1.6px}.page-heading{margin-top:12px}.page-heading h1{font-size:29px}.page-heading p{font-size:11px;margin-top:8px}.metrics{padding:27px 0 24px;gap:10px}.metrics strong{font-size:26px}.metrics>div{gap:9px}.metrics>div>span{font-size:9px}.metrics strong small{font-size:8px;display:inline;margin-left:4px}.resume{padding:27px 0 32px;gap:20px;align-items:flex-start;flex-direction:column}.resume h2{font-size:18px;margin-top:10px}.resume p{font-size:11px}.resume .primary{min-height:39px;padding:11px 16px}.section-heading{margin-bottom:13px}.section-heading h2{font-size:15px}.section-heading>span{font-size:9px}.subject-line{padding:20px 0;gap:15px}.subject-number{font-size:24px;min-width:29px}.subject-name h3{font-size:14px}.subject-name p{font-size:9px;line-height:1.8}.subject-name p span{padding:0 4px}.shelf-actions .text-button{font-size:10px;gap:4px;white-space:nowrap}.shelf-actions .icon{width:14px}.home-bottom{margin-top:30px;gap:25px}.heatmap{grid-template-columns:repeat(14,1fr)}.library-heading{padding:21px 22px 18px;gap:9px}.library-heading h1{font-size:21px;margin-top:5px}.library-heading h1 small{font-size:10px;margin-left:9px}.library-heading .eyebrow{font-size:7px;letter-spacing:1px}.library-actions{gap:14px}.library-actions .primary{font-size:11px;padding:10px 13px;gap:6px}.library-actions .text-button{font-size:11px;gap:4px}.library-actions .course-link{display:none}.filters{padding:0 22px 20px;gap:13px 20px;max-height:40dvh;overflow:auto}.filters label{width:calc(50% - 10px);min-width:0;max-width:none}.filters select{font-size:11px;max-width:100%;width:100%}.reset-filters{margin-left:0}.library-body{position:relative}.question-list{width:100%;border-right:0}.question-row{padding:17px 24px;border-bottom:1px solid #eef1e9}.row-top{font-size:12px}.row-preview{font-size:11px;line-height:1.8}.question-row.active{border-left-color:transparent;background:transparent}.group-title{padding:19px 24px 12px;font-size:11px}.question-detail{display:none;width:100%;height:100%;min-height:0}.mobile-detail .question-list{display:none}.mobile-detail .question-detail{display:block}.mobile-detail .library-heading{display:none}.mobile-detail .filters{display:none}.mobile-detail .filters-open .filters{display:flex;padding-top:18px}.detail-toolbar{padding:9px 17px;position:sticky}.mobile-back{display:inline-flex;font-size:11px;color:#6b7c62}.detail-position{margin-left:auto;margin-right:11px;font-size:11px}.detail-tools{gap:0}.detail-tools .icon-button{min-height:34px;min-width:29px}.detail-tools #favorite-button{margin-right:9px}.detail-tools .icon{width:17px;height:17px}.detail-content{padding:25px 24px 24px;min-height:calc(100% - 54px)}.question-path{font-size:9px;margin-bottom:18px;line-height:1.9}.question-heading{flex-direction:row;align-items:center}.question-heading h2{font-size:18px}.tag-toggle{font-size:9px;padding:7px 9px}.source-line{font-size:9px;margin:13px 0 22px}.question-body{font-size:var(--reading-size)}.transcript p{line-height:1.95}.option{font-size:calc(var(--reading-size) - 2px);padding:13px 14px;gap:12px}.option-key{font-size:16px}.submit-row{gap:14px;margin-top:24px;flex-wrap:wrap}.submit-row>span{font-size:9px}.attempt-result{gap:9px;align-items:flex-start}.attempt-result>div{gap:7px;align-items:center}.attempt-result span{display:block;width:100%;font-size:10px;margin-left:27px}.attempt-result .text-button{white-space:nowrap;font-size:10px}.solution{font-size:calc(var(--reading-size) - 2px);margin-top:25px}.study-tools{gap:16px;margin-top:28px}.question-footer{font-size:8px;flex-wrap:wrap;margin-top:28px}.desktop-hint{display:none}.stats-layout{padding:30px 0}.month-control{gap:4px}.month-control strong{font-size:10px}.calendar-day{padding:5px 0;gap:5px;aspect-ratio:1;min-height:34px}.calendar-day span{font-size:11px}.calendar-day small{font-size:7px}.calendar-grid{gap:4px}.calendar-section .section-heading{margin-bottom:15px}.subject-stat{min-height:60px;gap:10px}.subject-stat strong{font-size:11px}.subject-stat>span:not(.subject-dot){font-size:9px}.subject-stat .subject-dot{margin:0 3px}.subject-stat b{font-size:13px;min-width:35px}.settings-actions{gap:12px}.settings-actions .primary,.settings-actions .secondary{font-size:11px;padding:11px 14px}.settings-section p{font-size:11px}.settings-page>h1{font-size:28px}.lesson-toolbar{padding:17px 22px;gap:12px}.lesson-toolbar h1{font-size:18px}.lesson-toolbar span{font-size:9px}.lesson-toolbar>div:last-child{gap:15px}.lesson-toolbar .text-button{font-size:10px}.lesson-toc{display:none;position:absolute;inset:0 25% 0 0;width:auto;z-index:5;background:var(--bg)}.lesson-layout{position:relative}.toc-open .lesson-toc{display:block}#toc-toggle{display:inline-flex}#toast{bottom:calc(75px + env(safe-area-inset-bottom));font-size:11px;max-width:calc(100vw - 32px);min-width:180px;text-align:center;padding:11px 16px}.diagram-dialog{padding:10px}.diagram-scroll img{min-width:700px;max-width:none}.self-answer h3{font-size:11px}.self-answer .primary,.self-answer .secondary{font-size:11px;padding:10px 14px}}
@media(max-width:360px){.page{padding-left:20px;padding-right:20px}.detail-content{padding-left:20px;padding-right:20px}.topbar{padding-left:16px;padding-right:16px}.metrics strong{font-size:23px}.metrics strong small{font-size:7px}.metrics>div>span{font-size:8px}.subject-name h3{font-size:12px}.subject-number{font-size:22px;min-width:25px}.subject-line{gap:12px}.shelf-actions .text-button{font-size:9px}.subject-name p{font-size:8px}.question-heading h2{font-size:17px}.fixed-tags{gap:4px}.tag-toggle{padding:6px 7px}.detail-toolbar{padding-left:15px;padding-right:12px}.detail-position{margin-right:5px}.library-actions{gap:10px}.library-actions .primary{padding:9px 11px}.library-heading{padding-left:20px;padding-right:20px}.library-heading h1{font-size:20px}.library-heading .eyebrow{font-size:6px}.section-heading>span{font-size:8px}.subject-stat{gap:8px}.subject-stat>span:not(.subject-dot){font-size:8px}.subject-stat b{font-size:12px}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important}}

.question-body pre,.solution pre{font:14px/1.8 ui-monospace,SFMono-Regular,Menlo,monospace;background:#f6f8f2;border-radius:5px;padding:15px 18px;max-width:100%;overflow:auto;white-space:pre;tab-size:4}.question-body sup,.solution sup{font-size:.75em}.question-body sub,.solution sub{font-size:.75em}

.row-history{display:block;margin-top:7px;font-size:10px;line-height:1.5;color:var(--muted);font-variant-numeric:tabular-nums}.row-marks{flex-shrink:0}.question-history{display:flex;align-items:baseline;flex-wrap:wrap;gap:8px 14px;margin:12px 0 25px;color:var(--muted);font-size:11px;line-height:1.7;font-variant-numeric:tabular-nums}.question-history strong{font-size:16px;font-weight:500;color:var(--green)}.list-sentinel,.list-complete{padding:20px 14px;text-align:center;color:var(--muted);font-size:10px;line-height:1.7}